Film card with reference frame

ABSTRACT

A film card for use in an automatic microfilm display apparatus has a plurality of image frames, each bearing a marker image. One of the frames is a reference frame and includes only the marker image. The reference frame can be used for accurate positioning of a raster pattern on the remaining frames.

BACKGROUND OF THE INVENTION

This invention relates to apparatus for displaying information stored onfilm, and particularly to apparatus wherein an image on film isconverted into a video signal for display on a video terminal.

Prior U.S. Pat. No. 3,753,240 discloses an apparatus useful fordisplaying images contained on film. The apparatus includes mechanicalmeans for selecting a particular film, such as a microfiche card,locating that film in the operative position of a video signalgenerator, so that the image on the film can be converted into atelevision-type video signal, and the video signal provided to a displayfor display of the information contained on the film. This type ofsystem is particularly useful for retrieving information which is noteasily reduced to alpha-numeric format. For example, a great deal ofalpha-numeric data storage would be required to store the equivalent ofindividual's signature in conventional computer data storage equipment.This type of storage would require that the signature be encodedaccording to a code representing each segment of the signature, and itsrelative position with respect to the other segments of the signature. Alarge storage capacity would be required to permanently record thisinformation in a computer system and make it available for relativelyrapid display on a terminal in response to instructions by the operatorof the computer.

Systems for storing information, such as photographs or signatures, onmicrofilm have been known for years, and provide a relatively economicalstorage medium, since the information does not have to be reduced todigital format. Conventional microfilm storage systems require that thesystem user manually retrieve the individual film or microfiche cardfrom a file, and place it in a viewer in order to locate and display theindividual image which he desires to view. Prior U.S. Pat. No. 3,753,240discloses a system wherein such image information is stored onmicrofiche cards, which can be automatically retrieved and positioned inthe operative position of a video signal generator. The video signalgenerator then provides a television-type video signal representative ofthe microfiche image, and provides the signal for display on a remoteterminal.

This type of system is of particular advantage in applications whereinit is necessary to retrieve one of a large number of images from a filewithin a relatively short period of time. For example, when a customerpresents a check for payment at a bank, it is desirable that the bankteller check the signature on the check against the signature of thebanking customer which is on file. Typically, this requires that theteller leave his position, go to the central file, locate the card,compare the signature on the card with the signature on the check,return the card, and then return to his counter position to complete thetransaction. In accordance with the prior patent, it is envisioned thata cathode-ray terminal at the teller's counter location can be provided,which will display a microfilm stored image of the customer's signaturein response to the teller's command, consisting of, for example, thecustomer's account number. Thus, much time and effort can be saved andthe temptation to pay a check without verifying the signature isavoided.

The system disclosed in the prior patent has several disadvantages whichmake it difficult to implement the system in a practical environment. Inparticular, the prior system may experience difficulties in mechanicalcard retrieval. Also, it may not be able to adapt to microfilm imageshaving different quality levels, because of photographic processingchanges, and therefore different film density values for signature andbackground. Further, the prior art system makes no provision forhandling microfilm images having different polarities. The prior systemis adapted to provide only a single video image at any time. Therefore,in a bank with many tellers, it will be necessary for one teller tocomplete viewing a particular signature before another teller can haveaccess to the system to view a different signature. While the priorsystem does provide for the possible provision of a marker image in eachimage frame to facilitate the alignment of raster scanning patterns withthe frame, it is possible in accordance with the prior system that theframe image itself can interfere with the automatic operation of theelectronics which locates the marker image and aligns the raster inaccordance with the marker location. In addition, the prior system makesno provision for the possibility of there being multiple images on eachframe of the microfiche. In this case, it is desirable to change rastersize in order to provide a large display of the desired individualimage, by itself. It is also advantageous to blank portions of eachframe which contain information other than that to be displayed. Thisavoids operator confusion. The prior system also makes no provision forrotation of the raster pattern of the image detecting system so that theraster pattern can be aligned with the actual orientation of the imageon the film.

It is an object of the present invention to overcome these and otherdisadvantages of the prior system and to provide a complete andpractical system for the rapid display of image information stored onmicrofilm or other film storage medium, in a system controlled bycomputer generated signals.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided an improvement in afilm card containing a plurality of frames of film images, and adaptedto be used with a film reading apparatus having an adjustable imagesensing position. The apparatus is responsive to the detected locationof a marker image, associated with each frame of images, for adjustingthe location of the sensing position with respect to the film. Inaccordance with the improvement, a selected one of the frames is areference frame and includes only a marker image, so that the filmreading apparatus can detect the location of the marker image associatedwith the reference frame without interference from an informationcontaining frame image.

For a better understanding of the present invention, together with otherand further objects, reference is made to the following description,taken in conjunction with the accompanying drawings, and its scope willbe pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a system in accordance with thepresent invention.

FIG. 2 is a block diagram illustrating a portion of the FIG. 1 systemadapted for use with a plurality of displays.

FIG. 3 is a top view of a mechanical film selecting apparatus inaccordance with the invention.

FIG. 4 is a cross-sectional view of the FIG. 3 apparatus.

FIG. 5 is a circuit diagram illustrating a portion of the controlcircuit for the film positioning apparatus of FIG. 3.

FIG. 6 is a circuit diagram illustrating an optical switch for use withthe film selecting apparatus of FIG. 3.

FIG. 7 is a drawing showing a microfiche, usable in the apparatus ofFIG. 3.

FIG. 8 is a drawing illustrating the use of an individual frame of theFIG. 7 microfiche, for the storage of images of signatures.

FIG. 9 is a schematic diagram illustrating the deflection signalgenerating circuit for the FIG. 1 apparatus.

FIG. 10 is a schematic diagram illustrating one embodiment of the sizecontrol apparatus of the FIG. 9 deflection signal generating circuit.

FIG. 11 is a block diagram illustrating a deflection timing signalgenerating circuit usable with the circuit of FIG. 9.

FIG. 12 is a schematic diagram illustrating one embodiment of a rasterrotation control circuit usable with the FIG. 9 deflection signalgenerating circuit.

FIG. 13 is a block diagram illustrating one embodiment of a rasterrotation circuit usable with the deflection signal generating circuit ofFIG. 9.

FIG. 14 is a schematic diagram illustrating a dynamic focus controlsignal generating apparatus usable with the deflection signal generatingapparatus of FIG. 9.

FIG. 15 is a drawing illustrating the operation of the programmedmicroprocessor and marker detection logic of the FIG. 1 apparatus foranalyzing the location of a marker image.

FIG. 16 is a drawing illustrating a microfiche frame having lines ofencoded digital data.

FIG. 17 is a graph illustrating several lines of a video signalincluding signal portions respresentative of a marker image.

FIG. 18 is a block diagram illustrating the configuration of the markerrecognition circuit and peripheral equipment for analyzing the FIG. 17marker image representative video signals.

FIG. 19 is a block diagram illustrating the video signal processingapparatus of the system of FIG. 1.

FIGS. 20a and b are a schematic diagram of the FIG. 19 video signalprocessing apparatus.

FIG. 21 is a schematic diagram illustrating apparatus for controllingthe high voltage of the photomultiplier tube of the FIG. 20 apparatus.

DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram showing an embodiment of the inventionconfigured for use in a blank. As a typical embodiment, there is shownan arrangement wherein a microfilm display system is connected for usewith the general purpose computer of a bank. The arrangement isconfigured to respond to the entry of a customer's account number on akeyboard 32, and produce a display of the customer's signature on adisplay unit 66. The encrypted account number is supplied from keyboard32 to the bank's general purpose digital computer 30. The computer, byreference to the data memory 34, may supply the teller or operator withinformation concerning the customer's account, such as the accountbalance, and will also retrieve a microfilm address corresponding to thecustomer's signature. This film address is supplied to a microprocessor36, which comprises the principle control element in the microfilmdisplay system.

In response to the film address supplied by computer 30, microprocessor36 activates a mechanical film selection and positioning apparatus 38.The film selection and positioning apparatus 38 selects a microfilmunit, such as a microfiche card 44 and positions the appropriate frameof the microfilm in the operative position of a video signal generator,such as flying spot scanner 50 and photomultiplier tube 54.Microprocessor 36 performs all of its functions in accordance with acontrol program stored in programmable read only memory 40. A randomaccess memory 42 is also provided for storage of ephemeral data whilemicroprocessor 36 is performing the various functions required todisplay a particular signature on display 66.

Since a particular desired image may not be accurately located withrespect to the mechanical dimensions of film 44, because of variationsin the photographic processes by which the image is placed on the film,and since the intensity of the image on the film may also vary accordingto the film processing, the system shown in FIG. 1 has various devicesfor improving the location of the image with respect to the videodetecting apparatus, and for improving image quality. In particular,there is provided a sweep generator 46 which generates raster deflectionsignals for flying spot scanner 50 under the control of microprocessor36. A timing circuit 45 provides blanking of flying spot scanner 50during return intervals of the raster deflection signals. The sweepgenerator 46 may also provide focus control signals to the high voltagepower supply 52 in accordance with the location of the spot on theflying spot scanner. This function is commonly known as dynamic focuscontrol. The output of photomultiplier tube 54 is provided toexponential amplifier 56, which removes the natural logarithmic functionof the film image. A video processing circuit 57 converts the videosignal from the photomultiplier tube to a positive or negative polarityin accordance with a control signal provided by microprocessor 36 andalso provides inverted video signals to peak detector 58 which controlsthe voltage provided by high voltage power supply 60 to photomultipliertube 54. The photomultiplier tube voltage is varied in accordance withthe maximum peak video signal level in order to compensate for densityvariations in the film image.

Timing generator 45 provides horizontal and vertical deflection timingsignals to sweep generator 46 and also provides synchronization andblanking signals to video output circuit 62. In accordance with thesesignals, the video signal is blanked during the sweep return intervals,and appropriate synchronization signals for operation of display 66 arecombined to form a composite video signal. In addition, blanking signalsmay be provided to obliterate portions of the image of film 44 which arenot required to be displayed on the display 66. For example, if theimage being displayed is an individual signature, it is possible toprovide blanking signals to eliminate the video signal portionscorresponding to other signatures on the film.

In order to properly align the desired image from film 44 with the videodetecting apparatus, there is provided a marker image on the filmindicating the location on the film of the desired image. The videosignal produced by the video signal generator is provided to an analogto digital converter 64 which converts the analog video signal into adigital format. The digital signal is provided to marker recognitionlogic 65 which analyzes the signal and determines the location of themarker image with respect to the image detecting apparatus, consistingof flying spot scanner 50 and photomultiplier tube 54. The markerrecognition logic provides marker position signals to microprocessor 36which analyzes the position of the marker and calculates new positionsignals which are provided to sweep generator 46, which modifies thevertical and horizontal deflection signals provided to flying spotscanner 50, and thereby relocates the raster pattern with respect tofilm 44 so that the desired portions of the image are scanned by theflying spot scanner and the appropriate video signal is generated.Control console 37 is provided for controlling operation ofmicroprocessor 36 and displaying error messages generated bymicroprocessor 36.

FIG. 2 illustrates a variation of the FIG. 1 system wherein there areprovided multiple display units 66A, 66B, 66C, and 66D. Each of theseunits may correspond to a teller's position in a bank. When one image isto be displayed on a particular display unit, for example display unit66A, it may be desired that a different image be displayed on displayunit 66B. This may occur in a banking system, for example, when a tellerusing display 66A wishes to view the microfilm image corresponding to afirst customer's signature, and the teller using display unit 66B wishesto view another customer's signature. It also may be desired that athird teller wishes to view computer generated information on hisdisplay, such as the balance in a particular customer's account. Inorder to provide for a display of different images on the variousdisplays, it is necessary to continuously provide video signalscorresponding to the images to the displays. In order to accommodatethis operation, each of the display units is provided with acorresponding video switch 72A, 72B, 72C, and 72D. Each of theseswitches may connect its corresponding display unit directly to switch68, at the output of the video signal generating apparatus, or to one ofvideo memories 70A or 70B. Alternately, switches 72 may connect theircorresponding displays 66 to computer 30 through an appropriatecharacter generator 71 to receive computer generated video signals, forexample alpha-numeric data.

When one of the display units is to contain an image corresponding to afirst image on a film, microprocessor 36 causes the film selection andpositioning apparatus to locate that film in the operative position ofthe video detecting apparatus and generate a video signal correspondingto the image. Switch 68 connects the video signal generator to one ofthe video memories 70 and provides the video signal to the memory for anappropriate period, for example corresponding to one complete frame. Thevideo signal is thereby stored in the video memory, for example memory70A, and the vido memory may be used to regenerate the video signal andprovide the signal repeatedly to one of displays 66A, 66B, 66C, or 66Dthrough the corresponding swtich 72. While the video memory iscontinuously providing refreshed images on one of displays 66, anotherimage may be selected by microprocessor 36 and its corresponding videosignal stored in second video memory 70B for provision to anotherdisplay 66. While memories 70A and 70B are providing images to two ofthe display units, it is possible to provide still a third video signalto another display unit directly from the video signal generator byswitch 68 to the imput of another display switch 72. In addition, it ispossible to provide other information, for example, a video signalcorresponding to alpha-numeric data from computer 30 to one of thedisplays through an appropriate character generator 71. By use of thevideo switch arrangement shown in FIG. 2, it is possible to providesimultaneous display of different images while only a single image isplaced in the operative position of the video signal generator at anyparticular time. The operation of the various switches and memories isunder the control of the microprocessor 36, which determines which ofthe display units has called for a particular video signal, and sets theswitches appropriately, using the video memories as an intermediatestorage device as required.

FILM SELECTION AND POSITIONING

The film selection and positioning apparatus 38 shown as a block in FIG.1 is similar to the apparatus described in U.S. Pat. No. 3,429,436 toIrasek. In accordance with the Irasek disclosure, there is provided arotating drum on which there are arranged many microfiche cards. Theplane of each card is oriented parallel to the axis of the drum. Inorder to select a particular card, there is provided a film selectingapparatus which operates in conjunction with notches provided on clipson the edge of each card. The notches are coded so that each card hasits own particular notch pattern and as the drum is rotated anyindividual card can be selected by the film selecting apparatusaccording to the pattern of its edge clip notches. The apparatusprevents the withdrawal of any film card whose edge clip does notcorrespond to the pattern set up in the selecting apparatus.

FIG. 3 is a top view of the film selecting apparatus 38. There isprovided a chassis 74 upon which is mounted rotating drum 76. The drumis driven by a motor 82 which is connected by gear 84 to a gear 86 onthe drum. The film selecting apparatus 80 is provided with signalscorresponding to the card to be selected, and sets up a set ofmechanical film selecting plates in accordance with the notches on theedge clip of the card to be selected. As the card 44A approaches theselecting apparatus 80, it is withdrawn from its position within thedrum and caused to protrude to the position shown at 44B by magneticforces. Only the card whose edge clip corresponds to the plate patternset up in the selector 80 can be moved to the protruding position sincethe plates of selecting apparatus 80 prevent withdrawal of the remainingcards. A switch 87 is provided to detect the fact that the card has beenselected and partially withdrawn, and in accordance with the closing ofthe switch 87, the drum is caused to stop with the selected card inposition 44C, wherein a mechanical arm 92 having a clip engaging member94 engages the clip on card 44C and withdraws the card from the drum inorder to place it in an operative position with respect to the videodetecting apparatus, comprising flying spot scanner 50 andphotomultiplier tube 54. In accordance with the disclosure of Irasek,the timing of the stopping of drum 76 after the closing of switch 87 wasa constant time interval, independent of the speed of rotation of drum76. This constant time interval could therefore result in variations inthe position of card 44C when drum 76 comes to a halt, so that there maybe some difficulty in the operation of card engaging apparatus 94engaging clip 79 on the edge of each card 44.

In accordance with the present invention, there is provided animprovement in the control of the drum rotation to provide a moreaccurate stopping location, which is independent of the rotational speedof drum 76. In addition to the switch 87, which detects the selection ofone of the cards 44 in drum 76, there is provided a switch 88 whichcloses in response to the passing of each of the teeth on idler gear 85connected to drum gear 86. Using the circuit shown in FIG. 5, it can beseen that starting from the time of the closing of switch 87, apresettable counter 116 is provided with a series of pulsescorresponding to the passage of each of the teeth of gear 85 past switch88. A conventional flip-flop 112 is set by the closing of switch 87 andcleared when counter 116 has received a selected number of pulses. Thepulses from switch 88 are provided to counter 116 through AND gate 114.The output of the counter 116 change state when a selected number ofteeth have passed switch 88 and the corresponding number of pulses havebeen provided to the input of counter 116. This output sets flip-flop118 whose output causes the rapid stopping of motor 82 by use of themotor control circuit also shown in FIG. 5. Optically coupledtransistors 120 and 122 respond to the setting of flip-flop 118 bychanging from the conductive to the open condition. Opening oftransistor 120 causes the opening of transistor 124 and discontinues thesupply of positive voltage to armature coil 82A. Positive voltage isstill supplied to the field coil 82F of motor 82. The opening oftransistor 122 causes a positive going voltage to be supplied totransistor 126 causing that transistor to conduct and momentarily shortcircuit armature coil 82A. Motor 82 is then configured as a generatorwith a short circuit load. This load causes the motor to abruptly cometo a stop, thereby stopping the motion of drum 76 at an appropriateposition for arm 92 to engage the selected card 44. Since the current inarmature coil 82A is caused by the generator effect, and no furthercurrent is provided to armature 82A, since transistor 124 is in anonconducting state, the motor no longer turns until flip-flop 118 isreset by applying a control pulse to terminal 119.

Those skilled in the art will recognize that it is possible to usemicroprocessor 36 to perform the functions formed by discrete digitalcomponents 112, 114, 116, and 118. In such a configuration switches 87and 88 can be arranged directly as inputs to the microprocessor, and anappropriate program can be provided in read only memory 40 to controlthe operation of microprocessor 36 to perform the functions of the logiccircuits and provide an appropriate output signal for controlling theoperation of motor 82.

FIG. 6 shows an alternate embodiment of switches 87 and/or 88 wherein anoptical switch is used to provide the switching function, and generatethe appropriate output signal. Optical switch 128 includes a photo diodeand a photosensitive transistor whose optical path is caused to beinterrupted by card 44 or the teeth of gear 85. The output of the switchprovided by transistor 130 will be +5 volts when there is no obstructionin the optical path and will be at ground level when the optical path isobstructed. The use of an optical switch such as shown in FIG. 6eliminates problems which may be associated with mechanical switches,such as wear and tear on switch contacts, which may result in noise andcan effect the performance of the logic circuits used to control motor82.

FIG. 4 illustrates the X-Y positioning mechanism of the FIG. 3 selectionand positioning apparatus 38. After a particular film 44C has beenselected from drum 76, it is moved by positioning arm 92 in X-Ycoordinates in order to position a selected frame 108 in the operativeposition of the video detecting apparatus. In the embodimentillustrated, the video detecting apparatus includes a flying spotscanner 50, whose image 110 may be projected optically toward the photodetector 54. Detector 54 is contained within a housing 104 which has awindow to permit light emanating from the flying spot scanner 50 and itsassociated optics, and passing through a particular film 44, to beprojected into the photodetector tube 54. The flying spot scanner willgenerate a raster light pattern 110 on the film or the microfiche card44. The X-Y positioning apparatus will move the microfiche card 44 sothat the raster pattern 110, provided by the flying spot scanner, ispositioned over the frame of the microfiche 44. In the illustratedembodiment, positioning arm 92 moves in the direction X under theinfluence of an unseen stepper motor and gear 98 located within housing96. An additional stepper motor, also not shown, moves the positioningarm 92 in a track 100 in the Y direction indicated in FIG. 4. This X-Ypositioning under the influence of stepper motors is controlled bydigital signals provided from microprocessor 36 in accordance with thefilm address designated by computer 30 corresponding to, for example,the account number of the customer which has been entered on keyboard32. The apparatus illustrated in FIGS. 3 and 4 includes an opticalswitch 83 arranged to detect the end 81 of the edge 79 on film card 44as the film is withdrawn from rack 76. When the film is withdrawn to aparticular position, the end 81 of edge 79 should interrupt the lightpath of optical switch 83, which has the same configuration as switch 87shown in FIG. 6. The interruption of the light path provides a signal tomicroprocessor 36 indicating that card 44 has been successfullyselected, engaged and retrieved by the engaging means 94 on the end ofarm 92. In the event the card is not engaged and retrieved, themicroprocessor receives no signal from switch 83 and reinitiates thecard selection process. If the card is not selected after two or threetries, the microprocessor generates an error message for display on itsown control 37.

FIG. 7 illustrates the arrangement of individual frames on microfichecard 44. The card is provided with an edge clip 79, discussed above,which facilitates the selection of the individual card from the drumcontaining as many as hundreds of similar cards. Each edge clip hasunique identifying notches to facilitate selection of the card byselecting apparatus 80. In each card, there is provided a plurality offrames 132 and within each frame there is provided a marker image 134.The marker image may typically be a rectangular image having a highcontrast with the remainder of the frame. For example, if the frame is anegative image of a signature or multiple signatures, the marker imageis preferably a clear transparent area on the frame. On the other hand,if the frame image is a positive image of signatures havingpredominantly transparent image background, the marker image wouldappropriately be a high density black image. The marker image isprecisely located with respect to the information containing image ineach frame. In the embodiment illustrated, there are provided 22 columnsof frames each containing 16 frames so that the microfiche card containsa total of 352 individual image frames. In accordance with one aspect ofthe invention, a particular image frame, for example frame 136 isselected as a reference frame and is provided with no informationcontaining image. This frame merely contains a high contrast marker on abackground. The provision of one frame containing only the marker imagefacilitates the accurate positioning of the microfiche card and thepositioning of the light pattern generated by the flying spot scannerwith respect to the card images, as will be further explained.

FIG. 8 illustrates the format for a typical information containing frame132. The marker image 135 is located at the center of the top of theframe. There are provided 12 image spaces 138 each appropriate for animage comprising an individual's signature. The signature spaces areappropriate for containing signatures reduced by a factor of 42 times.Three signature spaces are contained in each quadrant of the frame. In asystem wherein multiple raster pattern sizes are available by variationof the deflection signals, it is possible and appropriate to provide afirst raster pattern equal in size to the entire frame for locatingmarker image 134, and adjusting the location of the raster with respectto the image bearing film, and thereafter use a second and smallerraster pattern to scan an individual quadrant of the frame. When thesecond raster pattern scans a quadrant of the frame, it provides a videosignal containing three individual signature spaces. Only one of thesespaces corresponds to the desired signature to be displayed on display66. The remaining two signatures can be removed from the displayed imageby providing an appropriate blanking circuit which generates a videosignal corresponding to no image during the raster scan intervalscorresponding to the undesired signatures. Blanking can also be achievedby blanking the beam on flying spot scanner 50 during portions of theraster which are not to be displayed. In this way there can be providedon display 66 an image consisting of only the desired signature, whoseaddress was specified by computer 30 in response to an entry on keyboard32. Microprocessor 36 can be used to control the appropriate blankingsignals in accordance with the film address. The microprocessor alsoprovides the appropriate control signals to sweep generator 46 forgenerating the larger and smaller raster patterns and the rasterposition signals to place the smaller raster pattern in the appropriatequadrant of the frame. As previously noted, microprocessor 36 alsoperforms the data analysis function which enables the microprocessor todetermine the location of marker image 134 with respect to the idealmarker image location in the raster pattern and adjust the rasterpattern location accordingly. The equipment to perform this process willbe discussed below.

DEFLECTION SIGNAL GENERATOR

FIG. 9 is a detailed schematic diagram of the deflection signalgenerator 46 for the FIG. 1 apparatus. The deflection signal generatorgenerates the appropriate horizontal and vertical deflection signals forthe operation of flying spot scanner 50. The deflection signals aregenerated in response to horizontal and vertical timing signals providedby timing generator 45 and also in response to signal regulating thechoice of horizontal sweep frequency, the horizontal and vertical sizeof the sweep pattern, and the horizontal and vertical position of thepattern. There may be additionally provided circuits for rotating theraster pattern as will be discussed below.

The circuit illustrated in FIG. 9 can generate raster signalscorresponding to standard 525 horizontal lines at a rate of 30 framesper second consisting of 60 interlaced 1/2 frames, or alternately cangenerate a 1,029 line raster rate. The choice of raster rate naturallydepends on the frequency of the horizontal timing signals supplied toterminal 142 from timing generator 45 and also in accordance with theoperation of switch 150 which chooses resistor 152 for the 1,029 linehorizontal drive or resistors 154 for the 525 line horizontal drive.

Amplifying circuit 146, consisting of amplifier 155 and transistor 157operates in conjunction with capacitor 156 to generate a ramp signal,which is rapidly reset by the closing of the switch 160 in response tothe horizontal timing signal supplied to terminal 142. The circuittherefore generates the indicated output signal consisting of a 0 to 5volt sawtooth signal. Differential amplifier 168 converts this signalinto a balanced raster signal which is supplied to size control unit172. Unit 172 consists of a variable resistance which regulates thevoltage sweep of the balanced sawtooth pattern, and thereby changes thesize of the resulting raster pattern on the flying spot scanner 50. FIG.10 illustrates one embodiment of a size control unit 172 wherein thesize can be one of two selected sizes according to the position ofswitch 188 which is controlled by a raster size signal supplied toterminal 189. In one position resistors 190 are placed in series withthe sawtooth signal to attenuate the signal and obtain a smallerhorizontal sweep on the flying spot scanner. In the other position noresistor is present in the circuit and a large raster results. Thoseskilled in the art will recognize that fully variable size or otherranges of size can be provided by other circuits.

The vertical deflecting signals are similarly generated by anothercircuit which includes amplifier 148 which operates in conjunction withcapacitor 162 to generate a relatively slower sawtooth pattern, thefrequency of which is regulated by vertical drive signals supplied toterminal 144 of switch 164. Amplifiers 146 and 148 are provided with 6.4volt signals from the 15 volt power supply by the use of a voltagedropping zener diode 156. The vertical deflection signal circuitincludes differential amplifier 170 and size control unit 174, which aresimilar to the units provided for the horizontal deflection signalcircuit.

In accordance with the invention, digital signals from microprocessor 36corresponding to a desired raster position are supplied todigital-to-analog converter 176. These signals provide an output analogvoltage corresponding to the desired horizontal position of the rasterpattern. The analog signal is added to the sawtooth signal at the outputof size control unit 172 and the combined signals provided to outputamplifier 184. Potentiometer 180 provides a horizontal positionadjustment.

Vertical position control signals from microprocessor 36 are alsoprovided to digital-to-analog converter 178 and are added into thevertical deflection sawtooth signals in similar manner. Likewisepotentiometer 182 is provided for adjusting the vertical position of theraster pattern. The combined vertical signals are provided to outputamplifier 186.

In addition to output amplifiers 184 and 186 there are provided poweramplifiers to increase the current of the horizontal and verticaldeflection signals to a value adequate to drive the deflection coils ofthe flying spot scanner.

FIG. 11 is a block diagram illustrating the functional components oftiming signal generator 45, which provides horizontal and verticaldeflection timing signals to terminals 142 and 144 of the deflectionsignal generator 46. In addition, the timing signal generator of FIG. 11generates composite blanking and sync signals for circuit 62 and timingsignals for marker recognition circuit 65. Oscillator 320 provides basictiming signals which are lowered in frequency by counters 322 and 326.Programmable read-only memories 324 and 328 convert timing signals fromcounters 322 and 326 to appropriate drive signals for sweep generator46. Signal generator 330 is programmed to provide the appropriatesynchronization and blanking signals.

FIG. 12 illustrates a circuit for providing a 90° rotation of thehorizontal and vertical deflection signals. By the use of circuit 192, asignal provided to input terminal 194 controls the electric switches,interchanging the terminals through which the horizontal and verticaldeflection signals are provided, so that the deflection raster patternof the flying spot scanner can be rotated through 90° in order toaccommodate an image which is in a rotated position on a microfiche.This rotation, when required for a particular image, can be indicated byaddress information provided to microprocessor 36, and microprocessor 36will thereby provide an appropriate control signal to terminal 194.

FIG. 13 illustrates a more versatile raster rotation device. The FIG. 13device provides for rotation of the raster pattern of the flying spotscanner by any arbitrary angle. The original generated horizontal andvertical deflection signals are provided to a combiner which can addportions of the horizontal deflection signals, in varying amplitudes andpolarities, into the vertical deflection signal; and can likewise addportions of the vertical deflection signal into the horizontaldeflection signal. Thus, by providing a mixture of horizontal andvertical deflection signals to both the horizontal and verticaldeflection terminals of flying spot scanner 50, the raster can be causedto assume any arbitrary angle with respect to the tube.

The FIG. 13 apparatus is capable of performing the deflection signalmixing function necessary to obtain arbitrary raster rotation. Asindicated, microprocessor 36 provides signals representative of thedesired horizontal and vertical position to D to A converters 320 and322 respectively, and also supplies multiplication constants K1, K2, K3and K4 to multipliers, 324, 326, 328 and 330. The constants are used tomultiply the horizontal and vertical deflection signals. These constantsare proportional to the sine and cosine of the desired rotation anglefor the raster. Thus portions of both X and Y deflection signals aresupplied by summers 336 and 338 to X and Y output amplifiers 340 and 342and thence to deflection coils 334H and 334V.

In order to use either the FIG. 12 of FIG. 13 raster rotation devices itis necessary to provide output power amplifiers for both the horizontaland vertical deflection signals which can accommodate the full range offrequencies experienced in the horizontal deflection signals. Likewise,it is necessary to provide a cathode-ray tube and deflection coils whichcan use high frequency signals for beam deflection in either plane.

FIG. 14 is a circuit diagram of apparatus 250 for providing dynamicfocus control signals for the high voltage power supply 52 for flyingspot scanner 50. It is a well known feature of flying-spot scanners thatspot defocuing occurs as the electron beam is deflected from its nominalposition near the center of the tube. This defocusing tends to increasethe spot size. When 525 line rasters are used, the spot size isadequately small, even with defocusing, so that interference betweenlines does not occur. When a 1,029 line raster is used the increasedspot size is significant with respect to the distance between rasterlines. Also deflection of the electron beam to the edges of the tube canresult in defocusing which is significant. even to the 525 line raster.In these cases, it is appropriate to provide dynamic focus control,which refocuses the electron beam by variation of the high voltageapplied to the tube in accordance with the deflection position of theelectron beam. The circuit 250 of FIG. 14 includes integrated circuits252 and 254 which generate output signals proportional to the square ofthe magnitude of the horizontal and vertical deflection signals. Theseoutput signals are combined in output amplifier 256 to form a compositedynamic focus control signal, which is illustrated in the drawing. Thissignal can be supplied to the high voltage power supply for flying spotscanner 60, and modulates the high voltage of the flying spot scanner toprovide dynamic focusing of the electron beam and maintain small spotsize, particularly when the 1,029 line scan is used.

RASTER POSITION CORRECTION

As noted above in connection with the description of the raster signalgenerating circuit of FIG. 9, horizontal and vertical digital rasterposition signals are supplied to the sweep generator circuit in order tomove the raster position to correspond to the position of a desiredframe on a film. In addition, the circuits of FIGS. 12 and 13 may beused to rotate the raster so that it corresponds with the angularorientation of the desired frame of the film. The determination of therequired raster location adjustment and rotation are made bymicroprocessor 36 acting under a program. Microprocessor 36 is suppliedwith digital data, derived from the video signal by the markerrecognition logic 65. The digital data corresponds to the location ofthe marker image on the desired or reference frame of the film.

Referring to FIG. 15, there is shown an area 110 corresponding to theraster scan area on a film by the flying spot scanner 50 used in theFIG. 1 apparatus. The area 110 is also shown by dotted lines in The FIG.4 drawing. Within area 110 there is located the marker image 134corresponding to the marker on one of the frames of the microfiche cardshown in FIG. 7. Marker image 134 may either be the marker image on thereference frame or the marker image on the desired information bearingframe. As is evident from FIG. 15, marker image 134 is not located atthe ideal marker position 258 in the raster pattern, and is alsooriented at a different angle from the desired frame orientation, sothat the edges of the marker image 134 are not oriented parallel andperpendicular to the horizontal direction of raster scanning.

When a frame containing marker image 134 in the orientation shown inFIG. 15 is scanned in a raster pattern, it can be determined byobservation of the resulting video signal that the marker image isdisplaced in both the X and Y directions from the nominal location ofthe marker image in the raster area, and it can also be determined thatthe marker image has an angular orientation which is different than thedesired orientation. Successive video signal outputs for individualhorizontal scan lines of the raster are illustrated in FIG. 17. Duringthe first horizontal scan H1, as shown in FIG. 17, the marker image isnot intercepted by the scanning light beam at all and the video signalrepresents a dark level (or a light level) depending on the filmpolarity. During the second scan H2, the flying spot intercepts marker134. This is indicated by area M1 in FIG. 17. During the third andsuccessive scan lines, portions of the marker are again intercepted bythe flying spot. The vertical location of the marker image with respectto the raster can be determined by the number of horizontal scan linesin the raster pattern before the flying spot intercepts the marker. Thehorizontal position of the marker with respect to the raster can bedetermined from the timing between the start of each horizontal scan andthe intercept of the marker. The angular orientation of the marker imagewith respect to the raster can be determined from the difference betweenhorizontal positions of the marker on successive horizontal scans.

The apparatus shown in FIG. 18 can be used to determine the vertical,horizontal and angular positions of the marker image from the videosignal. The video signal is provided to A to D converter 64, whichconverts the video signal into a digital signal. The digital signal isconverted to a binary signal by detector 332 wherein all incrementaltime intervals of the video signal having a voltage greater than aselected threshold V are assigned the value "1" and time intervals ofthe signal having a voltage below the threshold are assigned the value"0". Thus, the necessary measurements for determining the markerposition can be made only by counting the number of time intervalshaving a value of "1" before those having a value of "0". Discriminationof the marker image from other images is performed by width detector 334which must receive a selected number of successive "0" time intervalsbefore making a decision that the marker image representative signalportion has been encountered.

When width detector 334 determines that a segment of a marker image hasbeen detected, a marker image signal is sent to marker detection controlcircuit 335. Circuit 335 determines the clock count from a selecteddeflection timing signal, and supplies that count as a marker positionsignal to first-in, first-out memory 336 and eventually tomicroprocessor 36. In order to minimize the possibility of false markerdetection, a horizontal and vertical window may be defined correspondingto certain times with respect to the deflection timing signals withinwhich the marker is likely to be detected. The marker detection control335 and width detector 334 can then be activated to respond only tomarker representative signals within the window. This minimizes falsemarker detection alarms. Further assurance against false marker positionsignals is implemented in microprocessor 36 which compares the value ofeach marker position signal to previously received signals anddisregards any signal which has an unlikely value, e.g., far removedfrom the average of previously received signals.

In order to provide an indication of vertical positioning of the marker,memory 336 may be provided with data representing the identity of thehorizontal scan lines on which the marker image is detected. From thetiming data and scan line identification, microprocessor 36 candetermine the horizontal and vertical position of the marker image withrespect to the video detector. In addition, using deviations of markertiming data between scan lines, it is possible for microprocessor 36 todetermine the angular orientation of the marker image. This informationcan be used to generate raster angle control signals to be used in theraster rotation apparatus of FIG. 13.

Microprocessor 36 generates raster position control signals from thehorizontal and vertical data signals. The horizontal signals X₁ to X_(n)can be averaged to obtain the X correction. The last line Y on which amarker image is encountered determines the Y position. Corrections toproperly locate the marker with respect to the image detector by movingthe raster deflection pattern are generated by microprocessor 36 asdigital horizontal and vertical position signals and supplied to D to Aconverters 176 and 178 in the FIG. 9 circuit.

In a more complex system it is desirable to rotate the raster pattern inaddition to changing its location. In this event, the orientation ofmarker image 134 with respect to raster 110 must be determined bydetermining the difference between successive values of the horizontalposition data signal X. From these values, it is possible to generate asignal representative of the rotation of marker 134 from its nominalorientation, illustrated as 258. These rotation information signals canbe converted by the microprocessor 36 into appropriate multipliers K1,K2, K3 and K4 which are used in the apparatus of FIG. 13 to deriveappropriate horizontal and vertical deflection signals from the nominalhorizontal and vertical deflection signals generated by the deflectionsignal generator shown in FIG. 9. The horizontal and vertical positionsignals are also provided into the FIG. 13 circuit so that position aswell as orientation correction of marker image 134 can be achieved.

In many applications, where photographic images of a signature or personare to be provided to the display, it may not be necessary to providerotation of the image. In such systems, it is usually adequate toprovide correction of the position of marker image 134, and the amountof rotation experienced in ordinary film production will not requireimage rotation to make the image usable. In certain applications,however, it may be desired to provide digital information storage onmicrofilm type cards. In such situations, the microfilm image must beread by a flying spot scanner to generate digital data. The digital datamay be stored on the film image in strips 260, 262 shown in FIG. 16. Insuch applications, it is important that the flying spot scanner beaccurately aligned with the strips of digital information bearingimages, so that the flying spot scanner does not jump from one strip tothe next while reading the information. In this type of system, accurateorientation of the film image with respect to the raster is importantand the rotation circuit shown in FIG. 13 would be most useful.

The frame illustrated in FIG. 16 has a chevron shaped marker image 135instead of the rectangular marker image 134 shown in FIG. 15. This imageshape is slightly more complex for analysis by microprocessor 36, but isless subject to ambiguity. In this respect, vertical location withoutambiguity can be determined by computing the intersection of the twolines formed by the trailing edges of the image.

VIDEO PROCESSING CIRCUITRY

The video processing circuitry used in the film reading equipment ofFIG. 1 is shown in more detail in FIGS. 19, 20, and 21. FIG. 19 showsthe functions performed by the video processing circuitry in blockdiagram. The output of the photo multiplier tube is supplied to a videopreamplifier 56 which is provided with a black level correction circuit266-270. The black level correction circuit 266-270 operates to adjustthe output of the video preamplifier to the signal black level duringthe horizontal blanking intervals. This establishes the black signallevel to correspond to zero light input. The signal is then provided toa gamma correction circuit 274 and a video amplifier 276. The invertedoutput of the video amplifier 276 is supplied to a video peak detectorcircuit 58 which detects the peak of the inverted video signal, andthereby determines the minimum level of the video signal. This level issupplied to the photo multiplier tube power supply 60 as a controlinput, and is used to adjust the voltage supplied to the photomultiplier tube 54 in accordance with the density of the film actuallybeing viewed. Both the normal and inverted outputs of video amplifier276 are supplied to video polarity switch 281-283 which is controlled bya video polarity control signal. The appropriate polarity of the videosignal is selected according to a control signal representing filmpolarity and the signal with selected polarity is provided to thecomposite video generator 62 wherein composite synchronization andblanking signals are added to the video signal to provide a compositevideo output.

FIG. 20 shows a circuit for implementing the functions of the FIG. 19diagram. The black level correction circuit includes a switchingtransistor 270 which is closed by a horizontal blanking interval signalsupplied to terminal 272, and when closed connects the output ofamplifier 264 to capacitor 268. This performs a "sample and hold"function for the output of amplifier 264 during the horizontal blankinginterval. The signal stored in capacitor 268 is provided by amplifier266 as an input to amplifier 264 and adjusts the output of amplifier 264to a black level for input signals equal to the output ofphotomultiplier 54 during the no-light blanking intervals. This levelcan be adjusted by potentiometer 271.

Gamma correction circuit 274 consists of an arrangement of diodes andassociated resistors as shown in FIG. 20.

The gamma corrected video signal is supplied to amplifier 276 which isalso provided with inverted horizontal blanking signals from inverter278. The outputs of amplifier 276, consisting of normal and invertedvideo signals, are at ground level during the blanking intervals and atnormal signal level during the remaining time. A video polarity controlsignal is provided to terminal 284 and controls the operation oftransistor pairs 286 and 287. One of these transistor pairs is turned onand the other turned off for each condition of the polarity signal. Inaccordance with which transistor pair is turned on, the video signal isallowed to flow either through diode pair 280, 281 or through diode pair282, 283. The other pair of diodes is back biased so that no signalpasses. Thus, either the normal or inverted output of amplifier 276 isprovided to output composite video signal generating amplifier 62.Blanking switch 294 clamps the video signal to ground level duringhorizontal blanking intervals at the input to amplifier 62.Potentiometers 290 and 292 provide signal level adjustments for thevideo signal. Transistor 288 switches the level adjustment potentiometerin accordance with the input polarity signal. Also supplied to outputamplifier 62 is a composite synchronization signal supplied from timingsignal generator 45 over terminal 298. The level of the synchronizationsignal is adjusted by potentiometer 302. A blanking signal is suppliedby terminal 296 to switch amplifier 62 between video and synchronizationinputs. Potentiometer 300 adjusts the front and back porch levels of theoutput video signal. The output video signal is provided to outputterminal 303 from amplifier 62 and may be supplied to display 66.

The inverted video signal output from amplifier 276 is also provided toamplifier 304, which has two output channels. Both output channels areclamped to ground level by switches 306 which are closed during thehorizontal blanking intervals. One video signal is provided thourghterminal 308 to terminal 310 shown in FIG. 21 for use in controlling thehigh voltage supply to photomultiplier tube 54. The other output is aclamped video signal which is used for an input to the video A to Dconverter, or for conversion to digital data when the film imagerepresents data. The circuit shown in detail in FIG. 21 makes use of theauxiliary video output signal from amplifier 304, which has invertedpolarity, to adjust the power supply to the photomultiplier tube inaccordance with the density of the film which is being viewed. Peaksignal level of the inverted signal represents maximum light intensityor minimum film density. Capacitor 312 becomes charged in accordancewith the peak magnitude of the inverted video signal, and the resultingvoltage is supplied to amplifiers 314 and 316 for use as a controlsignal for power supply voltage control 318 which is connected in thepower supply for high-voltage power supply 60, which supplies highvoltage to photomultiplier tube 54. By the use of this circuit, thehigh-voltage supply for the photomultiplier tube is adjusted accordingto the minimum density of the film being viewed, and therefore theoutput video signal is automatically adjusted to compensate for changesin film density which are a result of film processing variations. It istherefore not necessary to have a highly controlled processing systemfor all films which are to be used with the display apparatus.

SYSTEM OPERATION

A further understanding of the operation of the microfilm displayapparatus of the invention will be had by the following description oftypical system operation using a system of the type shown in FIG. 1 fordisplaying a microfiche stored signature.

System operation is initiated by an operator entering an account numberor other identification information into keyboard 32. This informationis supplied to general purpose computer 30 which retrieves a filmaddress from data memory 34. The film address includes bits representinga particular microfiche card to be selected, the film polarity, theframe on the film corresponding to the desired signature and thesignature location on the frame.

The signature address signal is provided to microprocessor 36 bycomputer 30. Microprocessor 36 operates under a control program storedin programmable read-only-memory 40. The microprocessor starts thedisplay operation by supplying address and control signals to mechanicalfilm selection and positioning apparatus 38. The address signals set thecard selecting plates in selector 80 and the control signals initiaterotation of drum 76 by motor 82.

It should be noted that card selection depends only on card edge codingand is not dependent on the location of a card on drum 76. When theaddressed card passes selecting apparatus 80, it is partially withdrawnfrom drum 76 so that it engages feeler switch 87. Upon closing, switch87 provides a signal to microprocessor 36 which causes themicroprocessor to start counting pulses received from switch 88, whichprovides a pulse upon the passing of each tooth of gear 85. When themicroprocessor 36 has counted a selected number of pulses, it providesan output signal to a motor control circuit to cause the rapid stoppingof drum 76 with the selected card in the position 44C wherein it canbecome engaged by the engaging clip 94 on the end of positioning arm 92.Counting may also be achieved by the FIG. 5 circuit.

Microprocessor 36, after stopping drum 76 in the correct positionprovides a first set of control signals to positioning apparatus 38 tocause the arm 92 to withdraw card 44 and position the nominal locationof reference frame 136 in the operative position 110 of the videodetecting apparatus. The operative position consists of the rasterlocation for zero error of the reference frame location.

When the card is in position for reference frame 136, microprocessor 36provides control and nominal position signals to sweep generator 46 tocause the sweep generator to provide flying spot scanner 50 with nominalhorizontal and vertical deflection signals. These signals are of a sizeto provide a raster pattern corresponding to the size of the entireframe, and are at the nominal position and angular orientation of theframe. Where the frame is positioned at 90° rotation, the microprocessor36 can provide a control signal to cause the nominal raster pattern tobe supplied with this rotation.

As the flying spot scanner scans the reference frame 136, a video signalis generated which includes signal portions corresponding to markerimage 134 on reference frame 136. The marker image video signal isprovided to the marker recognition logic, which generates markerposition signals which are supplied to microprocessor 36. Themicroprocessor analyzes the marker image signals, and by reference toideal marker position data determines the positional variation of markerimage 134 from its nominal marker image location. If a raster rotationfunction is provided, the microprocessor 36 also determines the angulardeviation of the marker image from its nominal orientation. Once theposition of the marker image 134 on reference frame 136 has beendetermined by microprocessor 36, the position is stored and a controlsignal is provided to cause mechanical positioning apparatus 38 to movethe film card to a position wherein the frame containing the desiredimage is in the operative position of the video detecting apparatus.

When the desired frame is positioned, microprocessor 36 provides controland position signal to sweep generator 46 to cause the sweep generatorto generate horizontal and vertical deflection signals with a positioncorresponding to the position of marker image 134 on reference frame136, thus correcting the raster pattern for the position error ofreference frame 136. If rotational capability is provided, thedeflection signals are also compensated for the actual orientation ofthe reference frame marker position. The video signal generatingapparatus provides an output video signal corresponding to both themarker image 134 on the selected frame and the information bearingimages on the frame. This signal is provided to the marker recognitionlogic 65 which provides marker position signals to microprocessor 36.Again, the microprocessor analyzes the marker image data and determinesthe actual location of marker image 134 on the selected frame. Positioncontrol signals which center the raster pattern on the selected framecan then be generated.

The two-step process for positioning the raster pattern on the frame hasthe advantage of correcting major position errors between the imagelocation and the mechanical dimensions of the film card by use ofreference frame signals which have only a marker image, and correctingthe relatively minor frame-to-frame errors using the marker image on thedesired frame. This error is likely to be less than the card to frameimage error and the marker image can be more easily located near itsnominal position, even in the presence of information bearing imagesignals.

Having thus far located the actual image position on the selected frame,it is still necessary for the system to select and display only theimage portion which is desired, such as an individual signature.Assuming the desired images comprise signatures positioned on a frame inlocations 138 as shown in FIG. 8, the deflection apparatus must generatea smaller raster pattern centered on a frame quadrant corresponding tothe desired signature. Thus, microprocessor 36 changes the sweepgenerator control signals to generate a smaller raster and changes theraster position signals to compensate for the detected frame positionand rotation errors and to position the raster over the frame quadrantcontaining the desired image. The raster will then accurately sweep overa frame portion which contains three signature images. Only one of theseimages is desired. The other two images can be removed from the videosignal by microprocessor 36 providing a control signal to synchronizingand blanking circuit 62 to blank the signal protions corresponding tothe undesired images.

As noted, the output video signal is corrected for black level, imagedensity, and image polarity by the apparatus shown in FIG. 19. Wheremultiple displays are connected to a single film reading apparatus, thevideo switching circuits and memories shown in FIG. 2 are used under thecontrol of microprocessor 36 to provide multiple simultaneous videosignals to the displays.

While representative applications and embodiments of the invention havebeen described, those skilled in the art will recognize that manyvariations and modifications of such embodiments may be made withoutdeparting from the spirit of the invention and it is intended to claimall such variations and modifications as fall within the true scope ofthe invention

I claim:
 1. In a film card having horizontal and vertical edges andcontaining a plurality of frames of film images arranged in rows andcolumns within a photographic area, said frames having accurate frame toframe locations and less accurate frame to film edge locations, each ofsaid frames comprising an image area and having an identical markerimage within said image area, and adapted to be used with a film readingapparatus having an adjustable image sensing position, said apparatusbeing responsive to the detected horizontal and vertical location ofsaid marker image associated with each frame of images for adjusting thelocation of said image sensing position with respect to said film, theimprovement wherein one of said frames is a reference frame and includesonly said marker image, whereby said film reading apparatus can detectthe location of said marker image associated with said reference framewithout interference from an information-containing frame image.
 2. Theimprovement specified in claim 1 wherein each marker image comprises achevron-shaped image.